AC to DC converter

Abstract

An AC to DC conversion system is described. The conversion system consists of an electronic switch and control circuitry employed to provide controlled pulsed power to a storage device that provides power to a load at either a preselected or manually or automatic selectable voltages while ensuring the voltage drop across the switch is minimized to reduce power dissipated through the switch itself, thereby significantly increasing the efficiency and reducing thermal losses. The AC to DC converter in one minimal version consists of a pair of N-MOSFET transistors, a voltage divider, a storage element and a pair of diodes. The design enables high efficiency with minimal components that may be fully integrated onto silicon.

I claim: 
     
       1. An AC to DC conversion system for providing energy from an alternating current (AC) power source ( 101 ) in a direct current (DC) to an electronic load ( 107 ) at an output node ( 1005 ) comprising:
 a. a voltage divider ( 501 ,  502 ) connected across the load ( 107 ), and, 
 b. a first switch ( 504 ), having an input ( 1001 ) and an output ( 1002 ), connected through its input ( 1001 ) to the voltage divider, and, 
 c. a second switch ( 505 ), having an input ( 1003 ) and an output ( 1004 ), whose input ( 1003 ) is connected to the output ( 1002 ) of the first switch ( 504 ) through a current limiting resistor ( 801 ), and, 
 d. a storage capacitor ( 103 ) connected through a diode ( 304 ) to the output ( 1004 ) of the second switch ( 505 ), and, 
 e. a Zener diode ( 802 ), having a Zener voltage, connected between the input ( 1003 ) and output ( 1004 ) of the second switch ( 505 ) and a shunt capacitor ( 803 ) connected in parallel to the Zener diode ( 802 ) thereby clamping a voltage between the input ( 1003 ) and the output ( 1004 ) of the second switch ( 505 ) to the Zener voltage of the Zener diode ( 802 ), and, 
 f. the electronic load ( 107 ) connected to the storage capacitor ( 103 ). 
 
     
     
       2. The AC to DC conversion system of  claim 1  further comprising a series voltage regulator circuit interposed between the storage capacitor ( 103 ) and the electronic load ( 107 ), the series voltage regulator circuit comprising a pass transistor ( 106 ) having a characteristic threshold voltage (V T ) connected to the load ( 107 ) and a bias resistor ( 104 ) connected across the pass transistor, and, a Zener Diode having a Zener voltage (V Z ) connected to the bias resistor such that an output voltage to the load is maintained at V Z −V T . 
     
     
       3. The AC to DC conversion system of  claim 1  further comprising current limiting electronic circuitry interposed between the electronic switch and the energy storage element to limit the current flowing through the second semiconductor switch, the current limiting circuitry including a sense resistor ( 201 ) connected to the output of the second switch and the load ( 107 ) and a bipolar transistor ( 202 ) connected between the load and the input of the second switch. 
     
     
       4. The AC to DC conversion system of  claim 3  wherein all semiconductor devices are fabricated on a single integrated circuit chip. 
     
     
       5. The AC to DC conversion system of  claim 3  further including an isolation transformer between the storage capacitor and the electronic load. 
     
     
       6. The AC to DC conversion system of  claim 3  further including sense lines from the load passing through an isolator to the voltage divider thereby providing feedback control from the load. 
     
     
       7. The AC to DC conversion system of  claim 1  wherein the first switch and the second switch are both N-MOSFETs. 
     
     
       8. The AC to DC conversion system of  claim 1  wherein the first switch and the second switch are both bipolar transistors. 
     
     
       9. The AC to DC conversion system of  claim 1  wherein all semiconductor devices are fabricated on a single integrated circuit chip. 
     
     
       10. The AC to DC conversion system of  claim 1  wherein the voltage divider further includes a potentiometer ( 1401 ) such that an input voltage to the first switch is manually adjusted. 
     
     
       11. The AC to DC conversion system of  claim 1  wherein the voltage divider further includes a control MOSFET ( 1501 ) connected in place of a resistor of the voltage divider and an external DC control voltage, applied to the input of the control MOSFET ( 1501 ), thereby changing the voltage applied to the input of the first switch and changing the voltage stored on storage capacitor. 
     
     
       12. The AC to DC conversion system of  claim 11  wherein all semiconductor devices are fabricated on a single integrated circuit chip. 
     
     
       13. The AC to DC conversion system of  claim 1  further including an isolation transformer between the storage capacitor and the electronic load. 
     
     
       14. The AC to DC conversion system of  claim 1  further including sense lines from the load passing through an isolator to the voltage divider thereby providing feedback control from the load.